CN101383157A - Fly height compensation using read gain control loop - Google Patents
Fly height compensation using read gain control loop Download PDFInfo
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- CN101383157A CN101383157A CNA2008102157187A CN200810215718A CN101383157A CN 101383157 A CN101383157 A CN 101383157A CN A2008102157187 A CNA2008102157187 A CN A2008102157187A CN 200810215718 A CN200810215718 A CN 200810215718A CN 101383157 A CN101383157 A CN 101383157A
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B17/00—Guiding record carriers not specifically of filamentary or web form, or of supports therefor
- G11B17/32—Maintaining desired spacing between record carrier and head, e.g. by fluid-dynamic spacing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
- G11B5/6011—Control of flying height
- G11B5/6029—Measurement using values derived from the data signal read from the disk
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
- G11B5/6011—Control of flying height
- G11B5/607—Control of flying height using thermal means
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- Digital Magnetic Recording (AREA)
- Moving Of The Head To Find And Align With The Track (AREA)
Abstract
Apparatus and methods are disclosed that regulate head fly height so as to compensate for variation in height of a disk surface. An exemplary apparatus includes a circuit that detects disk height variation in response to variation in the gain of a variable gain amplifier, within an automatic gain control loop, that amplifies a read signal as the head reads from the disk surface. The circuit regulates the head fly height so as to compensate for the detected variation in disk height.
Description
Technical field
The present invention relates generally to sensor gap control, relate in particular to the flying height of the read/write head in the control data memory device.
Background technology
Data storage device (such as disk drives) allows host computer to store and retrieve a large amount of numerical datas with quick and effective and efficient manner.Typical disk drives comprises a plurality of magnetic recording discs, and they are installed on the rotatable wheel shaft of Spindle Motor and high speed rotating.The array of read/write head is set near the data storage surface of disc, so as between disc and host computer transferring data.Can these heads radially be positioned on the disc by revolving actuator and closed loop servo system, and these heads are flown near disc surface on air bearing.These comprise independent read element and write element usually.
By reading and writing data on the track narrower on the disc and, just can on disc, obtaining the higher density of data storage by keeping corresponding littler flying height gap between these and the data storage surface.The flying height of head can change according to an air density change in the disk drives and a temperature variation, may influence the therefrom outstanding distance (give prominence at bar-tip) in tip of head such as air density change when writing and a temperature variation.Some disk drives use well heater controllably to heat this head, to change this flying height.Some disk drives are attempted head fly-height is maintained nanoscale.Make head fly-height maintain in the acceptable scope this way along with this scope reduces to become more and more difficult to obtain the higher density of data storage gradually.May cause the contact that do not expect to have between the unacceptable read/write bit error rate and/or head and the data storage surface and potential data degradation and/or to the destruction of data storage surface in the operation outside the acceptable scope.
Summary of the invention
Regulate the flying height of head, with the height change of compensation disc surface.
In typical devices, a kind of circuit detects variation in disk height according to the change in gain of the variable gain amplifier in the automatic gain control loop, when this head variable gain amplifier amplified read signal when disc surface reads.This circuit conditioning head fly-height is so that compensate detected variation in disk height.
In another exemplary device, thereby a kind of circuit is regulated head fly-height by the heating that utilizes disk height compensating heater component value to regulate heating element, so that the height change of compensation disc surface.
In typical method, when disc surface reads, use the variable gain amplifier in the automatic gain control loop to come amplified read signal right overhead.According to the change in gain of variable gain amplifier, detect the height change of disc surface.Regulate head fly-height to compensate detected disc surface height change.
Description of drawings
Fig. 1 is the skeleton view with disk drives of the electronic circuit that disposes according to some embodiments.
Fig. 2 is the block diagram of the typical head disc assembly of disk drives.
Fig. 3 is the block diagram according to the part of the electronic circuit of the disk drives shown in Figure 1 of some embodiment configurations.
Fig. 4 is used for regulating head fly-height with the operation of compensation disc surface warp and the process flow diagram of method according to the change in gain of variable gain amplifier according to some embodiments.
Fig. 5 shows the curve map of the change in gain of the variable gain amplifier (VGAS) that is used for amplified read signal in the automatic gain control loop, also shows the bit error rate (BER) across wedge shape on the disc.
Fig. 6 shows according to the gain of some embodiment variable gain amplifiers the response of the power that offers the heating element that is used to heat this and the head fly-height curve map to the response of heating element variable power.
Fig. 7 shows according to the gain of some embodiments variable gain amplifier for each wedge shape curve map to the response of heating element variable power.
Fig. 8 shows according to some embodiments at the gain of a plurality of different wedge shape place variable gain amplifiers curve map to the linear evaluation function of the response of heating element power.
Fig. 9 shows the curve map of heating element value that can form the part of disc warpage compensating heater value form according to some embodiments, is used to compensate the disc warpage across a plurality of wedge shapes.
Figure 10 shows two curve maps, one shows when this and is reading and the change in gain of heating element power variable gain amplifier when being conditioned with compensation across the disc warpage of a plurality of wedge shapes, and another shows when this and is reading and the change in gain of heating element power variable gain amplifier when not being conditioned with compensation across the disc warpage of a plurality of wedge shapes.
Figure 11 shows two curve maps, one shows when this and is writing and the change in gain of heating element power variable gain amplifier when being conditioned with compensation across the disc warpage of a plurality of wedge shapes, and another shows when this and is writing and the change in gain of heating element power variable gain amplifier when not being conditioned with compensation across the disc warpage of a plurality of wedge shapes.
Figure 12 shows two curve maps, one shows the change in gain of variable gain amplifier when heating element power is conditioned with compensation across the disc warpage of a plurality of wedge shapes, and another shows the BER when heating element power is conditioned with compensation across the disc warpage of a plurality of wedge shapes.
Embodiment
Now with reference to accompanying drawing concrete exemplary embodiment of the present invention is described.Yet, can adopt many multi-form the present invention of enforcement, and should not be construed as limited to the illustrated embodiment of this paper; Yet, provide these embodiments can make this paper thorough and complete, and will transmit scope of the present invention to those skilled in the art.Shown in the accompanying drawing in the detailed description of specific exemplary embodiment used term be not intended to limit the present invention.
Should be appreciated that in this article, term " comprises " it being open, and comprises one or more described elements, step and/or function, and do not get rid of one or more not element, step and/or the functions of statement.In this article, singulative is intended to comprise plural form, unless context is clearly pointed out in addition.In this article, term " and/or " and "/" comprise any and all combinations of one or more relevant items of enumerating.Should be appreciated that although first, second grade of term can be used for describing various steps, element and/or zone, these steps, element and/or zone should be not limited to these terms.These terms only are used for a step/element/zone and another step/element/area region are separated.Thus, hereinafter first step/element of being discussed/zone also can be named as second step/element/zone, and does not deviate from content of the present invention.In the description of these figure, identical label refers to components identical.
The present invention can implement with hardware and/or software (comprising firmware, resident software, microcode etc.).As a result, in this article, term " signal " can adopt the form of continuous wave and/or discrete value, such as the digital value in storer or the register.
Hereinafter the block diagram of disk drives, disc, controller and the operation of the various embodiments of reference is described the present invention.Should be appreciated that the function/action in each frame can occur by the order beyond the operational illustration yet.For example, two frames that show in fact can be carried out basically simultaneously continuously, and perhaps these frames sometimes can be carried out by opposite order, and this depends on related function/action.Although some figure comprise that the arrow on the communication path may be main communication direction so that what to demonstrate, should be appreciated that, communication also can appear at shown on the opposite direction of arrow.
Fig. 1 shows the simplicity of illustration of disk drives (be often referred to and be decided to be 10).Disk drives 10 comprises disc stack 12 (being shown as single disc among Fig. 1), and Spindle Motor 15 makes disc stack 12 around main shaft 14 rotations (Fig. 2).Spindle Motor 15 is installed on the chassis 16.Actuator arm assembly 18 also is installed on the chassis 16.Disk drives 10 is configured to according to storing and retrieve data from writing with reading order of main process equipment.Main process equipment includes but not limited to desk-top computer, laptop computer, PDA(Personal Digital Assistant), digital video recorder/player, digital music recorder/player and/or can be coupled communicatedly with another electronic equipment of storage and/or retrieve data in disk drives 10.
Actuator arm assembly 18 comprises read/write 20 (or a transducer) of being installed on the bend arm 22, and bend arm 22 is attached to actuator arm 24, and actuator arm 24 can be around pivot bearing component 26 rotations.The read/write head, or be called for short head, 20 can comprise magnetic resistance (MR) element and/or film induction (TFI) element.Actuator arm assembly 18 also comprises voice coil motor (VCM) 28, and it makes 20 radially to move across disc stack 12.Spindle Motor 15 is coupled to controller, read/write channel circuit and other relevant electronic circuit 30 with actuator arm assembly 18, they be according to the configuration of at least one embodiment and can be loaded within one or more integrated circuit encapsulation of being installed on the printed circuit board (PCB) (PCB) 32.Controller, read/write channel circuit and other relevant electronic circuit 30 are called " circuit " hereinafter for short.Circuit 30 can comprise mimic channel and/or digital circuit (such as gate array), and/or can comprise the instruction of being carried out by one or more instruction processing apparatus based on microprocessor (such as general processor and/or digital signal processor).
Referring now to Fig. 2, disc stack 12 generally includes a plurality of discs 34, and each can have a pair of disc surface 36.Disc 34 is installed on the cylindrical shaft and Spindle Motor 15 makes disc 34 rotate around axle.Actuator arm assembly 18 comprises a plurality of 20, and each stature is oriented near in the disc surface 36 different one.Each stature 20 is installed on the corresponding bend arm 22.VCM 28 operation is with movement actuator arm 24, and these 20 are moved across its disc surface 36 separately.These 20 data recording surface 36 flights that are configured on mattress with respect to rotation disc 34, according to data being write on the data recording surface, perhaps read signal according to reading order reading of data from the data recording surface with generation simultaneously simultaneously from main process equipment from the write command of main process equipment.
Fig. 2 also shows track 40 and the spoke 43 on the disc 34.Data are stored within a plurality of concentric rail 40 (or cylinder) on the disc 34.Each track 40 is divided into a plurality of wedge shapes 42 of radially extending, and radially the spoke 43 of Yan Shening with these wedge shapes separately.Each wedge shape further is divided into servo wedge shape and data wedge shape.The servo wedge shape of disc 34 is used to positioning head 20 exactly, makes data to be write rightly on the selected disc 34 and from selected disc and reads.Servo wedge shape can comprise DC erase area, preamble area, servo address mark zone, orbit number zone, spoke zone and the servo zone of bursting servo the bursting of A, B, C, D of radial offset (staggered such as circumference and).The data wedge shape is a data part part, that receive of storage as main frame-startup write command, still can come the reading of data part according to main frame-startup reading order.
Some embodiments of the present invention relate to the warpage that compensation may occur on the disc surface 36, and this warpage may cause because use disc clamp that disc 34 is fixed on the main shaft 14.Thereby this disc clamp may make disc surface 36 warpages (bending) to disc 12 application of forces.May experience the disc warpage of maximum amplitude in the disc 12 near the interior diameter zone of main shaft 14 and disc clamp, the result produces maximum " head-disc " flying height and changes.In the disk drives of little form factor (such as less than 1.8 ＂ diameter discs), the disc warpage that clamping causes may be the most serious, and this is because the disc area that has used the largest face packing density and influenced by disc warpage on disc surface is relatively large.
Fig. 3 is the block diagram of a part of the electronic circuit of disk drives shown in Figure 1, and they are configured to portray disc warpage characteristic and compensation disc warpage.With reference to Fig. 3, typical 20 has a flying height (FH) with respect to disc surface 36 shown in the figure, and disc surface 36 is around main shaft 14 rotations.This 20 comprises read 300 (such as magnetic resistance (MR) element and/or film induction (TFI) element) and heating element 310.When read 300 reads from disc surface 36, produced and read signal.This reads signal and is amplified by head amplifier 320 at first, is next further amplified by variable gain amplifier 322, through low-pass filter 324 filtering, and is provided for and reads signal processing circuit 326.Read signal processing circuit 326 can operate in the usual way with detect through amplify and filtering read data in the signal, and can provide the sequence of detected logical one and 0 to recording controller 52.Recording controller 330 can to this data decode and to this data formatting so that be transferred to main process equipment.Main process equipment can include but not limited to desk-top computer, laptop computer, PDA(Personal Digital Assistant), digital video recorder/player, digital music recorder/player and/or can be coupled communicatedly with another electronic equipment of storage and/or retrieve data in disk drives 10.
Read signal processing circuit 326 and/or recording controller 330 and can provide the servo position that from disc surface 36, reads information to servo controller 332.Servo position information can be used to detect this 20 position with respect to the LBA (Logical Block Addressing) on the disc surface 36 (LBA).Servo controller 332 can use servo position information to make 20 an addressing track and a piece of seeking on the disc surface 36, and 20 maintenance is alignd with this track.
Gain by a Signal Regulation variable gain amplifier 322, this signal is called as variable gain amplifier gain signal (VGAS), and this signal automatic gain control circuit 328 produces in response to the signal that reads through filtering from low-pass filter 324.Automatic gain control circuit 328, variable gain amplifier 322 and low-pass filter 324 can constitute the automatic gain control loop, thereby the gain that it changes variable gain amplifier 322 by VGAS attempts to keep the constant relatively signal amplitude (this amplitude is provided for and reads signal processing circuit 326) that reads, and no matter magnetic transition Strength Changes on the disc surface 36 and head fly-height change.According to the figure that defines in the servo wedge shape (such as the gain control figure that wherein defines), the automatic gain control loop can change VGAS.As mentioned above, when disc read from track, the warpage of disc surface 36 had caused the variation of head fly-height.If do not regulate the disc surface 36 of head fly-height with compensate for warpage, the variation of then reading signal amplitude may cause the gain of variable gain amplifier 322 excessive variation and unacceptable the reducing of signal to noise ratio (snr) appearance of reading signal through amplifying to occur.What reduce reads signal SNR and may be limited on the disc surface 36 density of data storage that realizes reliably.
According to some embodiments, disc warpage compensating circuit 340 is provided, it portrayed disc surface 36 warpage scope and produce the form of a well heater value, these well heater values of scalable are with the feature of the disc surface 36 of compensate for warpage.20 when moving past the corresponding disc surface height change that sector on the disc surface 36 and radial zone and experience cause because of warpage right overhead, and flying height controller circuitry 350 uses disc warpage compensating heater values to regulate head fly-height FH.
Disc warpage compensating circuit 340 can comprise that modulus (A/D) converter 342, disc warpage portrayal unit 344, well heater are to VGAS response portrayal unit 346 and disc warpage compensating heater value form generation unit 348.Analog to digital converter 342 will convert digital VGAS to from the simulation VGAS (gain of its control variable gain amplifier 322) of automatic gain control circuit 328.Warpage distribution across the wedge shape of disc surface 36 is determined based on the distribution of digital VGAS in disc warpage portrayal unit 344.Disc warpage portrayal unit 344 can also determine across a plurality of radially elongated areas on the disc surface 36 (such as along the interior diameter zone, mid diameter zone and overall diameter zone, perhaps along the disc surface 36 radially elongated area (such as the grouping of track) that it defines of taking up an official post what) warpage distribute.Because disc warpage may be maximum along the interior diameter zone, so with compare along the mid diameter zone, along the interior diameter zone, disc warpage portrayal unit 344 may be used to represent the value that more multi-orbit VGAS changes within more wedge shapes and/or the wedge shape by record, determines the warpage distribution with higher fidelity; With compare along the mid diameter zone, along the overall diameter zone, disc warpage portrayal unit 344 may be used to represent within wedge shape still less and/or the wedge shape value that the VGAS of track still less changes by record, determines the warpage distribution with lower fidelity.
In addition, disc warpage portrayal unit 344 can produce first group of disc warpage portrayal value at first side of disc surface 36, and the disc warpage that next utilizes disc warpage symmetry on disc warpage and second side on the first group of disc warpage portrayal value and first side and opposite relevant supposition to produce opposite second side of disc surface 36 is portrayed.
Well heater changes the power that is added to heating element 310 to VGAS response portrayal unit 346 by a series of values, measure the variation of VGAS simultaneously so as therefrom to determine at least some wedge shapes of disc surface 36, VGAS is to the response of heating element variable power, and can determine this response at all wedge shapes of disc surface 36.Generation unit 348 distributes based on determined warpage and also based on the response of determined VGAS to the variable power that offers heating element 310, produces the value that is used for disc warpage compensating heater value form.Equally because disc warpage may be maximum along interior diameter zone, so with compare along the mid diameter zone, along the interior diameter zone, disc warpage portrayal unit 344 may produce more multi-orbit value within more wedge shapes and/or the wedge shape; With compare along the mid diameter zone, along the overall diameter zone, disc warpage portrayal unit 344 may produce still less within wedge shape and/or the wedge shape the still less value of track.
Flying height controller circuitry 350 comprises heater controller circuit 352 and disc warpage compensating heater value form 354, and this form comprises the value that is produced by generation unit 348.Form 354 comprises the well heater value, these values of scalable distribute (determined like that as portrayal unit 344) with the warpage of compensation disc surface 36, also scalable with compensation VGAS to the response of heating element variable power (as portray unit 346 determined).The well heater value is to define at least some radial zones at least some wedge shapes of disc surface 36, and can be at all radial zones definition in all wedge shapes of disc surface 36.For example, can define the well heater value, wherein the disc warpage that the one or more well heater values of definition arrive according to the VGAS measure of the change along a track in this radial zone with compensation in each radial zone at 16 radial zones across disc.
Heater controller circuit 352 is regulated the power that is added on the heating element 310 according to a value in the form 354 and 20 a current wedge shape and a radial position.For the compensating heater element power change with the head fly-height variation between response time, heater controller circuit 352 can be retrieved those values that is associated with a position (it is at least one wedge shape of 20 current fronts, wedge shape position) from form 354.For example, heater controller circuit 352 can be retrieved those values that is associated with that wedge shape of these four wedge shapes in front, current wedge shape position from form 354.Perhaps, for the response time between variation of compensating heater element power and the head fly-height, at least some values can be associated with skew wedge shape position in the form 354, such as being associated at that wedge shape that its that wedge shape front that produces data is offset the wedge shape of predetermined number with generation unit 348.Response time and dependency number purpose wedge shape and may be in front may depend on the operational power range of rotational speed, heating element 310 of disc surface 36 and heat-physical construction of 20.Fig. 4 is used for regulating head fly-height with the operation of the warpage of compensation disc surface 36 and the process flow diagram of method 400 according to VGAS according to some embodiments.With reference to Fig. 4, carry out certain operations in the frame 401, distribute such as the warpage of portraying disc surface 36 by disc warpage portrayal unit 344.For example, thereby can be by regulating the amplitude that reads signal and measure the distribution that VGAS determines warpage disc surface 36 along with the automatic gain control loop when the gain control figure that 20 read in the servo wedge shape of a plurality of orders, and can under the situation that the acquiescence power level is provided to heating element 310, carry out.When this head is reading to produce the different servo wedge shape (is VGAS
READ(wedge shape number)) VGAS when reading correlation, and (be VGAS when this head is writing with generation different servo wedge shape
READ(wedge shape number)) VGAS when writing correlation, can in frame 402, determine independent VGAS value.
Fig. 7 shows according to the gain of some embodiments variable gain amplifier 322 for each wedge shape curve map to the response of heating element variable power.With reference to Fig. 7, the size of observing sampling VGAS value across a plurality of wedge shapes to vibrate with warpage disc surface 36 corresponding roughly sinusoidal manner.Curve 702 is corresponding to the mean value that at the heating element power level is the VGAS value that records under zero the situation, and curve 704 is corresponding to the mean value that at the heating element power level is the VGAS value that recorded at 32 o'clock.Correspondingly, based on across a plurality of wedge shapes on the disc surface 36 with across the variation of the sampling VGAS value of a plurality of radial zones, the distribution that can measure warpage disc surface 36.
In frame 404, to analyze the VGAS value and have the wedge shape of the highest warpage size with identification, it is corresponding to the wedge shape with minimum VGAS value.Wedge shape with the highest warpage size is to have that of minimum VGAS value, because corresponding minimum head fly-height relatively provides the strongest relative signal amplitude and minimum relative VGAS value.Can define and be used for the VGAS value that the wedge shape in warpage reads and write and be target VGAS value, such as by under establish an equation and provide:
VGAS
READ_TARGET=min (VGAS
READ(wedge shape number)) and
VGASW
RITE_TARGET=min (VGAS
WRITE(wedge shape number))
Wedge shape with the highest warpage size also can corresponding to detect at first to the end 20 and disc surface 36 between the contact part, therefore, also can be used for limiting the acquiescence power level of heating element 310 based on the heating element power level that causes head-disc contact.
In order to determine how to revise the power that is added to heating element 310 so that compensate the disc warpage that records, in frame 406, measure of the response of VGAS value to the heating element variable power, such as measuring by the portrayal unit 346 of Fig. 3, this head reads from disc surface 36 simultaneously, and in frame 412,20 write simultaneously to disc surface 36.Determine VGAS response at each wedge shape on the disc surface 36, and can be at all wedge shapes and definite.Particularly, in frame 408, heating element power changes in a scope, and this scope may extend to than making a power level of the low threshold quantity of maximum power level of 20 contact disc surface 36 from zero-power level.At the heater power level place of each increase, can measure and write down the VGAS value.At each relevant heater power level and corresponding wedge shape number, i.e. VGAS
READ(well heater [0 ..., contact to earth-1], wedge shape number), can write down the measurement result of the VGAS value of gained.With reference to Fig. 4, in frame 410, can the definition wires sexual intercourse, it estimates the relation between VGAS value that (being similar to) records and the heater power level that is associated effectively.Correspondingly, each wedge shape can have a Linear Estimation function, defines this function so that VGAS value that records and heater power level associate.For each wedge shape (i), by producing one group of Slope Parameters (such as writing fashionable m
WRITE, the m when reading
READ) and the y-intercept point (write fashionable C
WRITE, the C when reading
READ), just can calculate the Linear Estimation function that the VGAS response distributes to heater power.It is that VGAS value for 0,50,100 and 150 is to the curve map of the various typical linear estimation functions of the response of heating element power level (being heating element digital to analog converter (DAC) register value) that Fig. 8 shows for the wedge shape number.For each wedge shape (i), by based on establishing an equation down to the heating element performance number (well heater DAC) that records with relevant VGAS value summation and ask slope value (m) and the y-intercept value (c) that on average just can determine the Linear Estimation function:
Between write operation and read operation, not marked change of Slope Parameters.Correspondingly, by use read with write operation shared Slope Parameters, can simplify the process that is used for determining the Linear Estimation function, and can realize that the corresponding of storer utilization reduces.Correspondingly, for specific wedge shape (i), it is as follows to define the slope that reads with write operation:
m[i]＝m
write [i]＝m
read [i]
Similar is, when when heating element is supplied with zero energy (well heater DAC=0), the intercept parameter that just is considered as specific wedge shape (c[i]) is nearly corresponding to sampling VGAS value.Correspondingly,, in this process of execution, just can obtain further to calculate to reduce by using the VGAS value at zero heater power place, as follows:
c
read[i]＝VGAS
read_zeroDAC[i] c
write[i]＝VGAS
write_zeroDAC[i]
The VGAS value can further be portrayed when 20 are writing data on the disc surface 36 to the response of heating element variable power in portrayal unit 346 in frame 412.Particularly, in frame 414, heating element power is to change in a scope, such as linking frame 408 above explained like that, and measure and write down corresponding VGAS value.In frame 416, such as by linking frame 410 the operation described above, define a linear relationship, it functionally estimates (be similar to) relation between the VGAS value that records and the heater power level of being correlated with.
Because write operation cause correct 20 have heat effect (this be with heating element 310 heat additional), thisly write the heating that causes and can be approximated to be constant, this constant is added to total output heater power.Correspondingly, the VGAS value can be used as skew constant relatively between the VGAS response to the response that is used for read operation and is used for the heating element variable power of write operation and is associated with each other.Thus, by the VGAS response that is identified for reading and next move the VGAS value of those fixed VGAS responses (increasing the y-intercept point), just can roughly simplify 20 when reading and writing the process of fashionable definite VGAS response to be identified for writing.The slope of the VGAS response that is used to write can be arranged to equal the slope of the fixed VGAS response that is used to read, just as above described at frame 416.By using VGAS
WRITE(wedge shape number, heating element power=0) is based on above at frame 414 the operation described, the y-intercept that can be identified for writing.
After the slope and y-intercept parameter of the Linear Estimation function of determining to be used on the VGAS response, can produce the well heater value now, during the disk height of the variation that causes because of warpage of 20 experience right overhead, at the disc warpage that records regulate (compensation) thus these values head fly-height is kept within the acceptable range.In frame 418, produced well heater value so that be used among the disc warpage compensating heater value form through compensating.Particularly, can be identified for the reading the well heater value and writing the well heater value through compensation of each wedge shape through compensation based on establishing an equation down:
Read well heater value (wedge shape number)=int[(VGAS
READ_TARGET-C
READ(wedge shape number))/m
READ(wedge shape number)]; And
Write well heater value (wedge shape number)=int[(VGAS
WRITE_TARGET-C
READ(wedge shape number))/m
WRITE(wedge shape number)],
At wedge shape number 0,1 ...., N.
Because the disc warpage along the interior diameter zone may be maximum, so can carry out the operation at frame 418 places, with compare along the mid diameter zone, along the interior diameter zone, can produce and be used for more multi-orbit more disc warpage compensating heater value within more wedge shapes and/or the wedge shape; With compare along the mid diameter zone, along the overall diameter zone, can produce and be used for still less within wedge shape and/or the wedge shape the still less disc warpage compensating heater value still less of track.
Fig. 9 shows the curve map according to the typical heater component value of some embodiments, and these values are all passed through and calculated with the disc warpage of compensation across a plurality of wedge shapes.20 when moving across a plurality of wedge shapes right overhead, can in a plurality of wedge shapes, ask on average to reduce noise the original heating element value of disperseing, shown in the curve map among Fig. 9 900, and can remove wherein systematic offset to promote through the use of the well heater value of compensation and the power that control offers heating element 310.Well heater value (Figure 90 0) through compensation is programmed in the disc warpage compensating heater value form 354 among Fig. 3.
As mentioned above, heater controller circuit 352 is regulated the power that is added on the heating element 310 according to the value in the disc warpage compensating heater value form 354 and also according to 20 current wedge shape and radial positions.
Figure 10 shows two curve maps, and one (curve map 1002) shows right overhead 20 change in gain that reading and regulating based on the disc warpage compensating heater component value (curve map 900) in the form 354 heating element power variable gain amplifier during across the disc warpage of a plurality of wedge shapes with compensation.Another curve map (1004) shows right overhead 20 change in gain that reading and do not regulating heating element power variable gain amplifier during across the disc warpage of a plurality of wedge shapes with compensation.
Figure 11 shows two curve maps, and one (curve map 1102) shows right overhead 20 change in gain that writing and regulating based on the disc warpage compensating heater component value (curve map 900) in the form 354 heating element power variable gain amplifier during across the disc warpage of a plurality of wedge shapes with compensation.Another curve map (1104) shows right overhead 20 change in gain that writing and do not regulating heating element power variable gain amplifier during across the disc warpage of a plurality of wedge shapes with compensation.Notice that in Figure 10 and 11, when regulating heating element power based on the disc warpage compensating heater component value (curve map 900) in the form 354 with compensation during across the disc warpage of a plurality of wedge shapes, the distribution of VGAS is more flat.Correspondingly, automatic gain control loop (such as variable gain amplifier 322, low-pass filter 324 and automatic gain control circuit 328) can produce through amplify and filtering read signal value so that by reading signal processing circuit 326 uses, these read signal value and have higher signal to noise ratio (S/N ratio), 20 also can obtain when reading from the warp zone of disc surface 36 right overhead.
Figure 12 shows two curve maps, and one (scattering curve Figure 120 2) shows the change in gain of the variable gain amplifier 328 when heating element power is conditioned with compensation across the disc warpage of a plurality of wedge shapes.Another curve map (1204) shows the bit error rate (BER) when heating element power is conditioned with compensation across the disc warpage of a plurality of wedge shapes.Correspondingly, Figure 12 shows right overhead 20 when reading from the warp zone of disc surface 36, and the use of disc warpage compensating heater component value can make the VGAS planarization and lower more consistent BER is provided.For example, under the situation of using the disc warpage compensation shown in the corresponding wedge shape 80 to 180 among Figure 12, can roughly improve when head fly-height appearing among Fig. 5 BER relatively poor relatively between the wedge shape 80 to 180 when regulating.Correspondingly, 20 across warpage disc surface 36 when mobile, by using disc warpage compensating heater component value to regulate the power that offers heating element 310, just can improve the signal to noise ratio (S/N ratio) that reads signal, and correspondingly improve the BER of the data that from disc 12, read.
With reference to Fig. 4, can determine when read/write that VGAS distributes, and compare to determine whether current well heater value has compensated the disc surface warpage fully with one or more threshold values, if do not have, operation that then can repeat block 401-420 is with further adjusting well heater value, and it is acceptable distributing up to the VGAS of gained.
In drawing and description, disclosed typical embodiment, although used specific term, only use them with general and descriptive meaning, and the hard-core meaning, this scope is illustrated by claims.
Claims (20)
1. device comprises:
Be used for detecting variation in disk height and regulating head fly-height, wherein variable gain amplifier amplified read signal when head reads from disc surface to compensate the circuit of detected disk height according to the change in gain of the variable gain amplifier in the automatic gain control loop.
2. device as claimed in claim 1, it is characterized in that, described circuit change in gain according to variable gain amplifier when head reads a plurality of different wedge shapes and the different tracks on disc surface produces disk height portrayal value, and portrayal is worth and regulates head fly-height according to disk height.
3. device as claimed in claim 2 is characterized in that, compares with the overall diameter zone at disc surface, and along the interior diameter zone of disc surface, described circuit produces and is used for more multipath to the disk height portrayal value of orbital position.
4. device as claimed in claim 2 is characterized in that, compares with the overall diameter zone at disc surface, and along the interior diameter zone of disc surface, described circuit produces the disk height portrayal value that is used for more wedge shapes.
5. device as claimed in claim 2, it is characterized in that, described circuit produces and is used for first group of disk height portrayal value of first disc surface, and utilizes the symmetry of the first group of disk height portrayal value and first and second disc surface and the relevant supposition of opposite warpage to produce the second group of disk height portrayal value that is used for the second opposite disc surface.
6. device as claimed in claim 2, it is characterized in that, described circuit produces the gain response value, the gain that described gain response value is used to represent variable gain amplifier is to the response of the variation that offers the power that is used for the heating element that the enemy heats, thereby described circuit is also regulated the power that offers heating element according to disk height portrayal value and the gain response value relevant with the position of head and regulated head fly-height.
7. device as claimed in claim 6, it is characterized in that, second group of gain response value when described circuit produces right overhead first group of gain response value when reading of data just and writing data right overhead, in reading of data, regulate heating element power by use disk height portrayal value and first group of gain response value, and by using disk height portrayal value and second group of gain response value when writing data, to regulate heating element power.
8. device as claimed in claim 6, it is characterized in that, described circuit uses disk height portrayal value and gain response value to produce disk height compensating heater value form, this form is identified at the variation of the heating element power of corresponding wedge shape and radial position place on the disc, and described circuit also is worth according in the disk height compensating heater value form at least one regulates head fly-height, and this at least one value is that the position according to head identifies.
9. device as claimed in claim 8, it is characterized in that, compare with the overall diameter zone at disc surface, along the interior diameter zone of disc surface, described circuit produces more value at more radial track location in disk height compensating heater value form.
10. device as claimed in claim 9 is characterized in that, compares with the overall diameter zone at disc surface, and along the interior diameter zone of disc surface, described circuit produces more value at more wedge shape in disk height compensating heater value form.
11. device as claimed in claim 8, it is characterized in that, described circuit is by the value that retrieval from disk height compensating heater value form and this a stature position of front, current wedge shape position are associated, and comes the response time between the respective change of the variation of compensating heater element power and head fly-height.
12. device as claimed in claim 8, it is characterized in that at least some values of disk height compensating heater value form are associated with the deviation post on the disc with the response time between the respective change of the variation of compensating heater element power and head fly-height.
13. device as claimed in claim 6, it is characterized in that, described circuit by zero and the power that is used for making the scope between the threshold power level more than the power level of contacting to earth of this touch disc surface repeatedly to change offering heating element and at disc surface on the corresponding change in gain of each wedge shape measurement variable gain amplifier, produce the gain response value.
14. device as claimed in claim 6, it is characterized in that, described circuit produces the gain response value by repeatedly changing the power offer heating element and measuring the corresponding change in gain of variable gain amplifier in a plurality of wedge shapes on the disc surface each; Described circuit produces the Linear Estimation of the gain of variable gain amplifier to the response of heating element variable power from the gain response value; And described circuit produces the gain response value that is used for a plurality of wedge shapes according to this Linear Estimation.
15. a device comprises:
The heating that is used to utilize disk height compensating heater component value to regulate heating element is to compensate the circuit that the disc surface elevation changes and then regulate head fly-height.
16. device as claimed in claim 15, it is characterized in that, the change in gain that the used disk height compensating heater component value of described circuit conditioning head fly-height is based on the variable gain amplifier in the automatic gain control loop produces, and described variable gain amplifier is used at head amplified read signal when a plurality of wedge shapes read on disc surface.
17. device as claimed in claim 16, it is characterized in that the gain that the used disk height compensating heater component value of described circuit conditioning head fly-height also is based on variable gain amplifier produces the response of the variation that offers the power that is used for the heating element that the enemy heats.
18. a method comprises:
When from disc surface, reading, use the variable gain amplifier in the automatic gain control loop to come amplified read signal right overhead;
According to the change in gain of variable gain amplifier, detect the height change of disc surface; And
Regulate head fly-height to compensate detected disc surface height change.
19. method as claimed in claim 18, also comprise: produce the gain response value, the gain that described gain response value is used to represent variable gain amplifier is to the response of the variation that offers the power that is used for the heating element that the enemy heats, wherein by regulating heating element power and then regulate head fly-height according to detected disc surface height change and the gain response value that produced.
20. method as claimed in claim 18, it is characterized in that, head fly-height is regulated according to disk height compensating heater component value, and these values are based on a position and the heating process selected and be used to regulate the heating element that the enemy heats.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US11/851,534 | 2007-09-07 | ||
| US11/851,534 US7508617B1 (en) | 2007-09-07 | 2007-09-07 | Fly height compensation using read gain control loop |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101383157A true CN101383157A (en) | 2009-03-11 |
Family
ID=40431584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2008102157187A Pending CN101383157A (en) | 2007-09-07 | 2008-09-02 | Fly height compensation using read gain control loop |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US7508617B1 (en) |
| CN (1) | CN101383157A (en) |
| SG (1) | SG151155A1 (en) |
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| CN104681043A (en) * | 2013-12-02 | 2015-06-03 | 株式会社东芝 | Disk storage apparatus and method for regulating head flying height before seek operation |
| CN106710608A (en) * | 2015-11-12 | 2017-05-24 | 株式会社东芝 | Correction value calculating method, manufacturing method of disk drive, and disk drive |
| CN107342719A (en) * | 2016-10-25 | 2017-11-10 | 北京市汉华环球科技发展有限责任公司 | A kind of scanning galvanometer motor driven systems |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104681043A (en) * | 2013-12-02 | 2015-06-03 | 株式会社东芝 | Disk storage apparatus and method for regulating head flying height before seek operation |
| CN106710608A (en) * | 2015-11-12 | 2017-05-24 | 株式会社东芝 | Correction value calculating method, manufacturing method of disk drive, and disk drive |
| CN106710608B (en) * | 2015-11-12 | 2019-05-17 | 株式会社东芝 | Compensating value calculation method, the manufacturing method of disk drive and disk drive |
| CN107342719A (en) * | 2016-10-25 | 2017-11-10 | 北京市汉华环球科技发展有限责任公司 | A kind of scanning galvanometer motor driven systems |
| CN107342719B (en) * | 2016-10-25 | 2019-11-12 | 北京市汉华环球科技发展有限责任公司 | A kind of scanning galvanometer motor driven systems |
Also Published As
| Publication number | Publication date |
|---|---|
| SG151155A1 (en) | 2009-04-30 |
| US20090067095A1 (en) | 2009-03-12 |
| US7508617B1 (en) | 2009-03-24 |
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